反复检查线路连接,没有找到原因,然后上网查了很多资料,有说USBtinyISP线路没有标识,可能接反的情况:
The 6-pin ICSP header isn't keyed so it is possible to plug the cable in backward. That is one thing you can check. The cable typically has a stripe on one side indicating Pin 1. You should make sure that is on the Pin 1 side both at your USBtinyISP and at your "Arduino".
http://arduino.cc/forum/index.php?PHPSESSID=789e12df2a8d107c6245e4d3b253c8bd&topic=153921.0